Mexico: Causes of Pemex explosion under investigation

Search and rescue operation in the PEMEX administrative building in Mexico City on February 01, 2013, a day after a deadly explosion. Pemex is stepping up security at oil production facilities as authorities investigate the blast, which killed at least 33 people at the state-owned company's headquarters. Read the full story.

Alfredo Estrella / AFP - Getty Images

General view inside the damaged building of state-owned Mexican oil giant Pemex in Mexico City, Mexico.